The field of the present invention is directed to a process for producing and applying an asphalt emulsion and, particularly, to a process for producing an oil-in-water asphalt emulsion, creating an aerosol from the asphalt emulsion using an atomizer and injecting the aerosol into an agitated coal stream.
Developing efficient means for producing alternative fuel sources is important in societies dependent on fuel. The process for developing synthetic fuel (xe2x80x9csynfuelxe2x80x9d) from coal is one such alternative. The synfuel process converts coal fines into a synthetic fuel through a chemical reaction with a petroleum-derived asphaltic binder. Asphaltic binders contain molecules with chemically reactive functional groups that can react with the feedstock coal fines to produce a synthetic fuel. As a result of these chemical reactions, such a synthetic fuel has a chemical composition that is significantly different from that of the feedstock.
According to one such synfuel process, the asphaltic binder is applied directly to the coal fines in a high-speed blender. This technology is effective in producing chemical change, but requires relatively high amounts ofbinder. Also, disadvantageously, the viscous melted asphalt is difficult to spread evenly onto coal fines and requires extensive mixing time.
According to another synfuel process, the asphaltic binder is applied in the form of an asphalt emulsion. The asphalt emulsion and the coal fines are mixed with to produce a rather gummy mixture. The asphalt emulsion generally comprises at least asphalt and water and may further include additives, such as various polymers to improve downstream processing. The resulting mixture of coal and asphalt emulsion is further processed. Pressure is applied to the mixture to expel the majority of the water, thus allowing the asphalt to more fully react with the carbon chain in the coal. Such asphalt emulsion processes involve the production of the asphalt emulsion at a central location and require that the resultant asphalt emulsion be shipped long distances. Accordingly, the asphalt emulsion must be relatively stable over a period of time. This often requires high levels of additives, such as soap or other stabilizers, to prevent premature breaking of the emulsion. An emulsion breaks when it spontaneously separates back into an oil phase and a water phase.
Hence, there exists a need for an improved asphalt emulsion-based synthetic fuel process, which overcomes the disadvantages of the existing processes.
An object of the present invention is to provide an improved process for introducing an asphalt into a synthetic fuel process.
A further object of the present invention is to provide an improved process for introducing an asphalt into a synthetic fuel process that allows for the debottlenecking of the synthetic fuel process.
A still further object of the present invention is to provide an improved process for introducing an asphalt into a synthetic fuel process that provides for higher throughput while still achieving the requisite chemical change necessary in a synthetic fuel process.
Another object of the present invention is to provide an improved process for producing an asphalt emulsion spray.
Yet another object of the present invention is to provide a more cost-effective way of producing an asphalt emulsion.
In order to achieve these and other objects, there is provided, in accordance with one aspect of the present invention, a process for introducing an asphalt into a synthetic fuel process, comprising the steps of introducing into the process an oil-in-water asphalt emulsion; passing the asphalt emulsion to an atomizer, adding to the atomizer a motivating gas to form an asphalt aerosol spray; agitating a coal fines feed stream; and injecting the aerosol spray into the agitated coal fines. The asphalt emulsion preferably comprises asphalt particles having an average diameter of about 5 microns or less. The asphalt emulsion can be anionic, cationic or non-ionic, more preferable anionic. The emulsion preferably has a pH of about 7.0 or greater. The asphalt preferably comprises no greater than about 50% by volume of the asphalt emulsion, more preferably about 30 to 50% by volume of the asphalt emulsion.
The introducing step preferably comprises manufacturing the asphalt emulsion upstream of the atomizer as part of a continuous, integral process for introducing an asphalt into a synthetic fuel process. The manufacturing step preferably comprises the further steps of introducing into the process an asphalt; creating a mixture of water and soap; mixing in a mixer the asphalt and the water and soap mixture to create an asphalt-soapy water mixture by passing the asphalt and the water and soap mixture along a common directional vector into a high turbulence mixing zone; and emulsifying the asphalt-soapy water mixture to create the asphalt emulsion. The asphalt preferably comprises no greater than about 50% by volume of the asphalt emulsion, more preferably about 30 to 50% by volume of the asphalt emulsion.
The aerosol of the spray preferably has a particle size of about 100 microns to about 500 microns. The atomizer preferably injects the aerosol spray as a flat spray. The gas is preferably selected from the group consisting of air, carbon dioxide, nitrogen and mixtures thereof. The agitated coal fines are preferably mechanically agitated. The mechanical agitating preferably involves continuously folding the coal fines. The aerosol spray preferably is generally evenly distributed over the coal fines.
In accordance with yet another aspect of the present invention, there is provided a process for spraying an asphalt emulsion onto coal in the manufacture of synthetic fuel, comprising the steps of introducing a motivating gas into an atomizer; introducing an oil-in-water asphalt emulsion into the atomizer; creating in the atomizer an atomized stream of emulsion and gas; and spraying the atomized stream onto an agitated coal fines stream. The asphalt emulsion preferably comprises asphalt particles having an average diameter of about 5 microns or less. The emulsion can be anionic, cationic or non-ionic, more preferably is anionic. The emulsion preferably has a pH of about 7.0 or greater. The asphalt preferably comprises no greater than about 50% by volume of the asphalt emulsion, more preferably about 30 to 50% by volume of the asphalt emulsion. The introducing step preferably comprises manufacturing the asphalt emulsion upstream of the atomizer as part of a continuous, integral process for introducing an asphalt into a synthetic fuel process. The manufacturing step preferably comprises the further steps of introducing into the process an asphalt; creating a mixture of water and soap; mixing in a mixer the asphalt and the water and soap mixture to create an asphalt-soapy water mixture by passing the asphalt and the water and soap mixture along a common directional vector into a high turbulence mixing zone; and emulsifying the asphalt-soapy water mixture to create the asphalt emulsion. The gas preferably is selected from the group consisting of air, carbon dioxide, nitrogen and mixtures thereof. The aerosol of the spray preferably has a particle size of about 100 microns to about 500 microns. The aerosol spray preferably is formed by mixing the asphalt emulsion and the motivating gas inside the atomizer. The atomizer preferably injects the aerosol spray as a flat spray. The agitating step preferably comprises mechanically agitating the coal fines. The mechanical agitating preferably involves continuously folding the coal fines.
In accordance with still another aspect of the present invention, there is provided a process for spraying an asphalt emulsion onto coal in the manufacture of synthetic fuel, comprising the steps of introducing into the process an asphalt binder; creating a mixture of water and soap; mixing the asphalt binder and the water and soap mixture to create an asphalt-soapy water mixture; passing the asphalt-soapy water mixture to an emulsifier; emulsifying the asphalt-soapy water mixture to create an oil-in-water asphalt emulsion; passing the asphalt emulsion to an atomizer; introducing a motivating gas stream into the atomizer; creating in the atomizer an atomized stream of emulsion and air, and spraying the atomized stream onto an agitated coal fines stream.
In accordance with still yet another aspect of the present invention, there is provided a mixer for mixing an asphalt emulsion and water, comprising a first flow chamber for receiving a first fluid at a first temperature; a second flow chamber joined to the first flow chamber, the second flow chamber including a third flow chamber housed within the second flow chamber, the third flow chamber for receiving a second fluid at a second temperature, wherein the flow chambers extend along a common directional vector; a fluid zone created by the area between the second and third flow chambers, wherein the first fluid is received within the fluid zone and the first fluid varies the temperature of the second fluid toward the temperature of the first fluid before mixing; a mixing zone for mixing the first and-second fluids to create a mixture; and an outlet for passing the mixture from the mixer. The second and third flow chambers are preferably in a pipe in a pipe relationship. The second flow chamber is preferably positioned at an angle of less than 90 degrees relative to the first flow chamber, as measured along their respective longitudinal axes. The first flow chamber and second flow chamber preferably form the arms of a Y and the outlet forms the base of the Y. The third flow chamber preferably terminates in the mixing zone. The end of the third flow chamber preferably forms a non-perpendicular angle relative to the longitudinal axis of the third flow chamber. The first flow chamber preferably includes a baffle. The baffle preferably extends into the first flow chamber a depth substantially equal to the end of the third flow chamber in the mixing zone.
In accordance with still yet another aspect of the present invention there is provided a mixer for an asphalt emulsion and a water-based mixture, comprising a first ingress having a baffle, wherein the ingress allows entry of a stream of soapy-water into the ingress; a second ingress comprising a first pipe and a second pipe positioned in the first pipe, the pipe in a pipe structure forming a concentric longitudinal area between the pipes, the inner pipe allowing for the flow of an asphalt binder and the concentric area allowing for the passage of soapy-water about the inner pipe, wherein the first and second ingress extend along a common directional vector; a junction area, wherein the first and second ingress meet to allow for the mixing of the asphalt binder and the soapy-water; and an egress which allows for flow of the mixture of soapy-water and asphalt mixture from the mixer. The second ingress preferably is positioned at an angle of less than 90 degrees relative to the first ingress, as measured along their respective longitudinal axes. The first ingress and second ingress preferably form the arms of a Y and the egress forms the base of the Y. The second pipe preferably terminates in the junction area. The end of the second pipe preferably forms a non-perpendicular angle relative to the longitudinal axis of the pipe. The baffle preferably extends into the first ingress a depth substantially equal to the end of the second pipe in the junction area.
In still yet another aspect of the present invention there is provided a process for spraying an asphalt emulsion onto coal in the manufacture of synthetic fuel, comprising the steps of introducing into the process an asphalt binder; creating a mixture of water and soap; mixing the asphalt binder and the water and soap mixture to create an asphalt-soapy water mixture, wherein the water and soap mixture and the asphalt binder are introduced into a mixer along a common directional vector and the asphalt binder is progressively cooled in the mixer, prior to mixing with the water and soap mixture; passing the asphalt-soapy water mixture to an emulsifier; emulsifying the asphalt-soapy water mixture to create an oil-in-water asphalt emulsion; continuously passing the asphalt emulsion to an atomizer; introducing an air stream into the atomizer; creating in the atomizer an atomized stream of emulsion and air; and spraying the atomized stream onto an agitated coal fines stream.
In accordance with a still further aspect of the present invention there is a process for producing an asphalt emulsion for use in manufacturing synthetic fuel, comprising the steps of introducing into the process an asphalt binder; creating a mixture of water and soap; mixing the asphalt binder and the water and soap mixture to create an asphalt-soapy-water mixture, wherein the water and soap mixture and the asphalt binder are introduced into a mixer along a common directional vector whereupon the asphalt binder is progressively and indirectly cooled by the water and soap mixture prior to mixing with the water and soap mixture; and emulsifying the asphalt-soapy water mixture to create an oil-in-water asphalt emulsion capable of being continuously applied. The progressive cooling preferably comprises introducing the water and soap mixture to the mixer through a first flow chamber; introducing the asphalt binder to the mixer through a second flow chamber; and passing at least a portion of the water and soap mixture into a third flow chamber, the second flow chamber being housed within the third flow chamber, wherein the water and soap mixture progressively cools the asphalt binder as the asphalt binder flows through the second flow chamber. The process preferably comprises the additional steps of passing the cooled asphalt binder and the water and soap mixture to a mixing zone and mixing the asphalt binder and the water and soap mixture.
In accordance with still yet another aspect of the present invention, there is an asphalt emulsion for use in manufacturing synthetic fuel, consisting essentially of an asphalt binder; water; and a soap at about 0.5 to 4% by total emulsion weight.
In accordance with still yet another aspect of the present invention there is a process for continuously applying an oil-in-water asphalt emulsion in a synthetic fuel process comprising the steps of creating an aerosol spray including a motivating gas and an asphalt emulsion; and continuously spraying the aerosol spray into a source of agitated coal fines.
The present invention provides multiple improvements including the ability to continually mix heated asphalt and a soapy water mixture to create an emulsion characterized by very small asphalt droplets and to apply same uniformly to coal fines in the production of synfuel. The invention provides for good contact between the coal fines and the asphalt and an efficient use of the asphalt as a result of its uniform application. Thus, the present process avoids processing disadvantages associated with batch processing. In addition, the present invention provides a more cost effective way of producing an asphalt emulsion and an atomized asphalt emulsion spray. Namely, the process requires reduced amounts of soap. An additional advantage to the process of the present invention is that it utilizes a continuous scheme of making emulsion, in contrast to a batch scheme wherein the emulsion remains unused for periods of time. Additionally, the emulsion form of asphalt divides the asphalt into extremely fine particles with very high surface area. This fine division, along with the relatively low viscosity of the emulsion facilitates spreading the binder much more uniformly across the surface of the coal fines, increasing interfacial contact between coal and binder. Increased interfacial contact between the binder and coal results in increased levels of chemical reaction and more efficient use of binder. Mixing time also is reduced. With increased efficiency, higher throughputs of synfuel can be realized using the same processing equipment. Furthermore, the emulsion of the present invention uses significantly less amounts of soap and requires no heavy oils or additives, such as synthetic polymers, because the continuous process of the invention allows utilization of an emulsion with a lower stability. The lower amount of soap utilized in the emulsion of the invention reduces the cost of the manufacturing of the emulsion. Finally, a method of applying the emulsion of the invention to the coal fines by aerosolization, or atomization, also results in a lower cost to produce synfuel. The asphalt emulsion producing process of the present invention allows a reduced amount of asphalt to be utilized, thus reducing significantly costs associated with the manufacturing of the synthetic fuel.
Other objects, features and advantages of the present invention will become apparent from a review of the detailed description of the preferred embodiments, including the illustrative drawings and the appended claims which follow.